The Inter-university Consortium for Political and Social Research (ICPSR) will make data from the 2000 Census of Population and Housing of the United States available to researchers in a broad array of fields, especially population and aging. In doing so, it will collect, preserve, enhance, and distribute data developed by the U.S. Census Bureau. ICPSR will also provide training to data users and data librarians. The project will lead to great economies of scale by facilitating the work of researchers. These activities will be conducted by ICPSR, and also involve collaborative arrangements with the Census Bureau and with the Population Studies Centers of the University of Michigan and the University of Minnesota. This project has six key activities: (1 ) Acquisition and long-term archiving of data produced by the 2000 Censuses of Population and of Housing. (2) Re-formatting census data to facilitate use in statistical analysis programs. (3) Development of documentation for census data that is compliant with the Data Documentation Initiative (DDI) standard. (4) Development of new data products, including special subsamples and special summary files, that serve the special needs of academic researchers. (5) Provision of web-based access to the data. The web-based system will include a data-finder and custom subsetting capabilities to allow researchers to find and acquire the data needed for specific research applications. (6) Provision of training and outreach activities to encourage use of the data. The Census is a unique source of data for a wide range of research topics about the United States. With the funding requested here, ICPSR proposes to collect and preserve those data, to add them to its large collection of data from earlier censuses, and to distribute those data and information about them widely.